Automatic clock spring rewind mechanism



3, 1966 J. L. HANCOCK 3,267,659

AUTOMATIC CLOCK SPRING REWIND MECHANISM Filed May 4, 1964 United States Patent I 3,267,659 AUTOMATIC CLOCK SPRING REWIND MECHANISM John L. Hancock, Villa Park, Ill., assignor to Mastercrafters' Clock Corporation, Chicago, 11]., a corporation of Illinois Filed May 4, 1964, Ser. No. 364,424

' 4 Claims. (Cl. 58-41) 'This invention relates generally to improvedmechanisms for automatically rewinding clock springs and more particularly to improvements in means'forintermittently energizing anelectric motor for rewinding a clock spring. More specifically, the invention relates to a new and improved switching means for intermittently energizing a clock spring rewind-motor.

Electrically operated mechanisms for automatically and intermittently rewinding the power springs of clocks are of course old and well-known. In general, such mechanisms comprise a cog wheel which is connected to the mainspring and also geared to the motor drive shaft. Switch means is provided for energizing the motor, and switch closing means is provided for intermittently closing the switch means at some desired predetermined time interval. In the usual clock assembly, the switch closing means is mechanically associated with the mainspring shaft, and the interval between rewindings isapproximately seven and one-half minutes.

Those skilled in the art will appreciate that the accuracy of a clock will in some degree be affected by the exactitude with which each rewinding cycle is repeated. Similarly,

any uneven wear or corrosion which upsets the delicate balance of the gear train and associated parts will adversely affect the clocks accuracy and/ or result in actual failure of the rewinding mechanism. In these respects, the switch means comprises a critical part of the rewind mechanism. Heretofore, such switch means were char- 7 acterized by certain disadvantageous features which frequently affected the efficiency and life of the clock and militated against the more universal acceptance of the rewind mechanisms. The major disadvantage of the prior switch means resided in the fact that they were not positive acting and thus too slow or irregular in their operation. As a result of the slow and inefficiently made and broken electrical contact, undesirable arcing or heat occurred which ultimately corroded or pitted the associated members.

It is therefore an import-ant object of this invention to provide an improved automatic clock spring rewind mechanism which overcomes all of the disadvantages described hereinabove.

Another object is to afford an automatic clock spring rewind mechanism of the character described having novel switch means which are positive acting to make substantially instantaneous closingand opening of the motor circuit. Undesirable arcing and heat is thereby virtually eliminated.

A further object is to provide an automatic clock spring rewind mechanism of the character described having switch means which does not impede the normal stopping lag or running inertia of the motor.

Still another 'object is to afford an automatic clock spring rewind mechanism of the character described having means for diverting electric current which might otherwise flow undesirably through the mainspring shaft bearings and other associated gear parts.

Yet another object is to provide an automatic clock spring rewind mechanism of the character described which may be inexpensively manufactured and yet is most durable and efiicient for the purposes intended.

With the foregoing and other objects in view which will 3,267,659 Patented August 23, 1966 appear'as the description proceeds, the invention consists of certain novel features of construction, arrangement and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the form, proportion, size and minor details of the structure may be made without departing fromthe spirit or sacrificing any of the vadvantages of the invention.

For the purpose of facilitating an understanding of my invention, I have illustrated in the accompanying drawings a preferred embodiment thereof, from an inspection of which, when considered in connection with the following description, my invention, its mode of construction, assembly and operation, and many of its advantages should be readilyunderstood and appreciated.

Referring to the drawings in which the same characters of reference are employed to indicate corresponding or similar parts throughout the several figures of the drawrugs:

FIG. 1 is a fragmentary rear elevational view of an automatic clock spring rewind mechanism embodying the principles of the invention;

FIG. 2 is a fragmentary side view thereof;

FIG. 3 is a sectional view taken substantially on the plane of irregular line 33 in FIG. 1 and viewed in the direction indicated; FIG. 4 is a fragmentary view similar to FIG. 2, with portions removed and showing the relationship of parts immediately after closing of the switch means;

FIG. 5 is a fragmentary view similar to FIG. 1, but with portions removed and showing the relationship of parts just prior to activation of the switch means from the open condition;

FIG. 6 is an enlarged detail view showing the coaction of parts at the instant prior to closing of the switch means;and

FIG. 7 is a view similar to FIG. 5, but showing the relationship of parts immediately after the switch means have moved to the closed condition.

Since the standard clock members comprise no part of this invention, only so much thereof will be described as is necessary for an understanding of my present invention.

Referring more particularly to the various figures of the drawings, it will be seen that the reference numeral 10 indicates generally an automatic clock spring rewind mechanism embodying the principles of the invention. The mechanism 10 comprises a motor 12 having a drive shaft 14 which carries a worm gear 16. The motor 12 may be of the direct current type and includes conductor terminals such as 18, 18 for electrical connection to a power source such as a small battery (not shown).

A cog wheel or spring winding gear 20 is operatively meshed with the worm gear 16. The cog wheel 20 is made of an electrically nonconductive material, such as nylon, and a pair of reduced diameter contact plates 22 and 24 is positioned on both sides thereof as indicated in FIGS. 2 through 4. The cog wheel 20 and contact plates 22 and 24 are mechanically connected together as a unit and are formed with an arcuate slot 25 therethrough for reasons which will become apparent as the description proceeds. The plates 22 and 24 are also electrically connected.

The cog wheel 20 is loosely mounted on the mainspring shaft 26 of a clock movement. A customary output gear such as 28 is rigidly mounted on the shaft 26 and a power spring or mainspring 30 is likewise mounted on said shaft. One end 32 of the mainspring 30 is connected to the output gear 28 and the opposite end 34 is connected to the cog wheel 20 (see FIG. 3).

A switch plate indicated generally by the numeral 35 is loosely mounted on the shaft 26 and is keyed to the or less.

cog wheel 20. The switch plate 35 is made of an insulating material such as nylon, and the same comprises balanced and opposed segments such as 36 and 38. A drive pin 40 projects integrally from the outer face of the segment 36, and a finger 42 is integrally formed on the inner face of said segment. The finger 42 is slidably received within the slot 25 thereby keying the plate 35 to the cog wheel 20, although it will be appreciated that relative movement is permitted between said plate and wheel within the limits of the arcuate length of the slot.

Turning now to FIG. 6 of the drawings, it is important to note that segment 38 of the plate 35 includes a leading face 44, an outer face 46 and a rear face 48. In the embodiment illustrated, the outer face 46 and rear face 48 afford a sharp corner or edge 50 therebetween and preferably, the angle described by said corner should be 90 It should be understood, however, that the particular angles or dimensions illustrated for the various segment faces may take any desired form consistent with the cooperation of said segment with the electrical contact in a manner which will subsequently be described.

Rigidly mounted on the mainspring shaft 26 is a drive 'arm 52 which is in aligned relationship with the drive pin 40. It .will thus be appreciated that each complete revolution of the shaft 26 brings the arm 52 into a position where it engages the pin 40 as illustrated in FIG. of the drawings.

Opposed spring metal brushes or contact wipers 54 and 56 are connected to a suitable insulating block such as 58 mounted on a mounting plate 60, and said wipers are adapted to normally bear respectively against the contact plates 22 and 24. Each of the wipers 54 and 56 may be bifurcated as indicated, and in the embodiment illustrated, the free or bearing ends thereof are provided with an angular bearing surface 62 (see FIG. 6) whose function will subsequently be described. The wipers 54 and 56 may include suitable conductor terminals such as 64 and 66 for'electrical connection to the battery, motor and/or a common ground in the usual manner. The common ground may comprise one of the mounting plates such as 60 normally found in clock movements for supporting the gear trains.

Operation of the mechanism may now be described in the following manner. As the mainspring 30 unwinds, it causes the shaft 26 and drive arm 52 to rotate in the counterclockwise direction as indicated by the arrows in FIGS. 5 and 6. While wiper 54 is in constant contact with contact plate 22, wiper 56 normally rests upon the outerface 46 of the plate segment 38 so that the electrical circuit is normally open. When the drive arm 52 reaches the position shown in FIG. 5, it engages the drive pin 40 and causes the latter to move with it, such movement being made possible by the movement of the finger 42 within the slot 25. When the switch plate 35 has rotated sufficiently, the segment 38 achieves thep'osition relative to the Wiper 56 which is illustrated in FIG. 6. In this position, it will be noted that the angular bearing surface 62 bears against the corner 50 with the forcecomponents indicated by the arrows. As the segment 38 continues to move to the right, the wiper 56 literally shoves the same and snaps away and downwardly therefrom to make substantially instantaneous contact with the contact plate 24. The relative positions of the described members is now as indicated in FIG. 7.

With the electrical circuit closed, the motdr 12 is energized and causes a relatively rapid counterclockwise rotation of the cog wheel 20. As the cog wheel rotates, the trailing edge of the slot engages the finger 42 thereby coupling the member 35 thereto. Rotation of the member 35 continues until the wiper 56 rides up on the leading face 44 of the segment 38 to provide a substantially instantaneous breaking or opening of the electrical circuit. The open circuit de-energizes and stops the motor 12 and the wiper 56 once again rests upon the outer face .46 of the plate segment 38. It will be appreciated that as the wiper 56 rides up on the segment 38, the drag created thereby is virtually negligible so that the motor is desirably permitted to coast to a complete stop at which time the wiper will likewise come to rest on the outer face 46.

Those skilled in the art will appreciate that the described snap action of the wiper 56 may be achieved equally well by causing the wiper to fall off of or cam away from the plate segment 38 or a combination of both causes. Thus, while there is both falling and camming in the embodiment illustrated, the wiper bearing surface 62 may be eliminated entirely and the angle described by the corner 50 may be made larger than if desired. Likewise, the leading segment face 44 need not be angular as illustrated, but may even be vertical so long as the wiper 56 is suitably configured to cooperate therewith to afford a camming action which results in a substantially instantaneous breaking of the circuit.

Upon completion of the foregoing winding cycle, the drive pin has been rotated to the opposite or trailing side of the drive arm'52, so that said arm may now make another complete revolution before the cycle is repeated. During each cycle, the mainspring 30 is of course rewound to its original condition of tension. In this respect, the invention contemplates the use of a mainspring which constantly operates between full tension and one revolution less than full tension. Thus, each rewinding cycle brings the mainspring 30 back to full tension.

The wipers 54 and 56 are electrically connected serially, although the wiper 54 desirably is in parallelism with the common ground. This affords an alternate circuit through the wiper 54 which diverts substantially all of the electrical current from flowing through the clock movement parts such as the shaft 26 and output gear 28. However, aside from this desirable diversion of the electric current, the mechanism 10 would function even if the wiper 54 were eliminated. Similarly, although the cog Wheel 20 has been described as a non-conductor having a pair of contact plates 22 and 24 connected thereto, the same may also comprise an integral metal conductor having one'or both of the wipers associated therewith.

It is believed that my invention, its mode of construction and assembly, and many of its advantages should be readily understood from the foregoing without further description, and it should also be manifest that while a preferred embodiment of the invention has been shown and described for illustrative purposes, the structural details are nonetheless capable of wide variation within the purview of my invention as defined in the appended claims.

What'I claim and desire to secure by Letters Patent of the United States is:

1. In an automatic clock spring rewind mechanism including a winding gear, and an electric motor having an energizing circuit for rotating said gear, the improvement comprising a contact plate on a face of said gear comprising an element of said circuit,

a wiper in said circuit adapted toengage said contact plate to complete said circuit,

a thin switch plate connected to said contact plate in parallel abutting relationship therewith for spacing said wiper from said contact plate to open said circuit,

means permitting relative movement between said switch plate and said contact plate, and

drive means for periodically rotating said switch plate independently of said contact plate whereupon said wiper cooperates with said switch plate to snap therefrom and make substantially instantaneous contact with said contact plate.

2. The mechanism of claim 1 in which said switch plate comprises a pair of radially opposed segments,

one of said segments having an angular leading face,

an outer face, and

a trailing face,

said trailing face and outer face forming a sharp corner therebetween.

3. The mechanism of claim'2 in which said wiper comprises a spring metal member having a free end normally bearing against said outer face,

said free end including an angular bearing surface,

said angular bearing surface cooperating with said corner when said plate has been sufficiently rotated independently of said winding gear to push said one switch segment away and thereby make said substantially instantaneous contact with said contact plate.

4. An automatic rewind mechanism for a clock having a shaft and a mainspring mechanically connected at one end thereof to said shaft, said mechanism comprising an electrically non conductive winding gear loosely mounted on said shaft and mechanically connected to the opposite end of said mainspring,

a pair of contact plates connected to the opposite faces of said winding gear,

said contact plates and winding gear being formed with aligned arcuate slots therethrough,

an electric motor having an energizing circuit including one of said contact plates,

a worm gear on the drive shaft of said motor meshed with said winding gear,

a first resilient metal wiper in permanent engagement with one of said contact plates for diverting electric current from said clock shaft,

a second resilient metal wiper in said energizing circuit adapted to engage said other contact plate to complete the circuit,

said second wiper having an angular bearing surface at the free end thereof,

a thin electrically non-conductive switch plate loosely mounted on said clock shaft in face-to-face engagement with said other contact plate,

said switch plate comprising radially opposed first and second segments, an integral finger projecting inwardly from said first segment and slidably received in said aligned slots, an integral drive pin projecting outwardly from said first segment, said second segmentincluding an angular leading face,

a planar outer face and a trailing face, said trailing face and outer face affording a sharp corner therebetween defining an angle between zero and and a drive arm rigidly mounted on said clock shaft outwardly of said switch plate, said drive arm cooperating to engage to said drive pin with each revolution of said clock shaft to rotate said switch plate independently of said winding gear whereupon said second wiper bearing surface cooperates with said corner to push said second switch plate segment and snap away therefrom to make substantially instantaneous contact with said other contact plate, said second wiper bearing surface further cooperating with said second switch plate segment to make a substantially instantaneous break of contact with said other contact plate when said angular leading face moves therebeneath in unison with said winding gear.

- References Cited by the Examiner UNITED STATES PATENTS 1,639,990 8/1927 Feldcamp 58-4O 1,806,969 5/1931 Fowler -40 3,113,639 12/1963 Koplar et al 185--40 LOUIS J. CAPOZI, Primary Examiner.

LEO SMILOW, Examiner.

GERALD F. BAKER, Assistant Examiner. 

1. IN AN AUTOMATIC CLOCK SPRING REWIND MECHANISM INCLUDING A WINDING GEAR, AND AN ELECTRIC MOTOR HAVING AN ENERGIZING CIRCUIT FOR ROTATING SAID GEAR, THE IMPROVEMENT COMPRISING A CONTACT PLATE ON A FACE OF SAID GEAR COMPRISING AN ELEMENT OF SAID CIRCUIT, A WIPER IN SAID CIRCUIT ADAPTED TO ENGAGE SAID CONTACT PLATE TO COMPLETE SAID CIRCUIT, A THIN SWITCH PLATE CONNECTED TO SAID CONTACT PLATE IN PARALLEL ABUTTING RELATIONSHIP THEREWITH FOR SPACING SAID WIPER FROM SAID CONTACT PLATE TO OPEN SAID CIRCUIT, MEANS PERMITTING RELATIVE MOVEMENT BETWEEN SAID SWITCH PLATE AND SAID CONTACT PLATE, AND DRIVE MEANS FOR PERIODICALLY ROTATING SAID SWITCH PLATE INDEPENDENTLY OF SAID CONTACT PLATE WHEREUPON SAID WIPER COOPERATES WITH SAID SWITCH PLATE TO SNAP THEREFROM AND MAKE SUBSTANTIALLY INSTANTANEOUS CONTACT WITH SAID CONTACT PLATE. 